The Hauptman-Woodward Medical Research Institute seeks to replace an obsolete Rigaku RU- 200 rotating anode x-ray generator with another rotating anode, the Rigaku MicroMax-007 microfocus unit. With the Micromax we are also requesting a Rigaku Saturn 944+ CCD detector and related equipment, the whole comprising a complete X-ray data collection system. The RU-200 was purchased in 1992, and Rigaku has announced that the machine will no longer be supported. Irreversible failure could happen at any time, and the need for replacement is urgent. The Institute currently houses two image plate detectors, one a MAR 345 unit on loan from Stanford and the other our workhorse, an R AXIS IV sited on a RU-H3RHB generator. The MAR unit is dedicated to a collaborative project with Stanford on robotic crystal mounting, and is rarely available for normal data collection. There are 11 NIH-funded projects - plus a slew of more preliminary ones - seeking time on the R AXIS IV, and the queue is often discouragingly long. We feel that the need for a second general purpose data collection system is compelling. HEALTH RELEVANCE: Protein molecules carry out most of the functions in living organisms, and many drugs work by targeting proteins involved in a disease process. The requested equipment will allow us to create three-dimensional images of various protein molecules. These images greatly expedite and refine the process of designing drugs by letting us tailor the drug to its complementary site in the protein.